The embodiments herein generally relate to gas turbine exhaust assemblies and, more particularly, to deswirler vanes disposed in such exhaust assemblies, as well as a method of reducing swirl in exhaust assemblies.
Gas turbine exhaust ejectors typically include a high-velocity primary flow that leaves a turbine engine and transmits momentum to a surrounding medium by shear forces, thereby mixing with and directing the surrounding medium into a secondary flow. The primary and secondary flows then proceed into a secondary component having a larger diameter and referred to as a shroud. The flows are sensitive to residual swirl from the turbine exhaust and the swirl can be particularly high at operating conditions such as idle conditions, for example. Deswirl vanes are commonly used to address the swirling portion of the flow, but these vanes extend fully through the exhaust flow path.
Certain advantages and disadvantages are associated with fully extending vanes and assemblies with no vanes at all. In particular, low and high power exit swirl angles are such that engine compartment pumping is compromised because of the resultant flow field at the interface between the primary and secondary flows. No vanes allow high temperature exhaust gases to flow back into the engine compartment at low/high power conditions. Deswirl vanes are used to handle highly swirling engine flows and mitigate engine compartment backflow. However, at high engine power conditions, deswirl vanes generate losses because high power turbine exit swirl angles cause the flow to impact the deswirl vanes, thereby causing excessive exhaust system losses.